1. Field of the Invention
The present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition which is suitable for use in an ultramicrolithography process applicable to a process for manufacturing such as a manufacture of a super-LSI or a high-capacity microchip, a process for fabricating a nanoimprint mold, a process for producing a high-density information recording medium, and the like, and other photofabrication processes, and is able to form a high definition negative-tone pattern using an electron beam or extreme ultraviolet rays, an actinic ray-sensitive or radiation-sensitive film using the same, mask blanks including an actinic ray-sensitive or radiation-sensitive film, a pattern forming method, and a photomask. Particularly, the present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition which is suitable for use in a photofabrication processes using a substrate having a specific underlying film, an actinic ray-sensitive or radiation-sensitive film using the same, mask blanks including an actinic ray-sensitive or radiation-sensitive film, a pattern forming method, and a photomask.
2. Description of the Related Art
In the production process for semiconductor devices such as ICs and LSIs, it is a practice in the related art to perform microfabrication by lithography using a photoresist composition. Recently, the formation of an ultrafine pattern in the submicron region or quarter-micron region has been demanded in accordance with the realization of high integration for integrated circuits. In accompaniment with this, a trend of wavelength shortening in the exposure wavelength from g-rays to i-rays, further to an excimer laser light can be seen, and in recent years, developments in lithography using an electron beam, X-rays has been progressed.
In particular, electron beam and extreme ultraviolet ray lithography are positioned as pattern forming technology of the next generation or a more advanced generation and are also widely used for manufacturing a photomask which is used for a semiconductor exposure because of high resolution. For example, in a process for manufacturing the photomask by electron beam lithography, after a resist layer is formed on a shielding substrate provided with a shielding layer consisting mainly of chrome or the like, and further an electronic beam exposure is selectively conducted, an alkali development is performed to form a resist pattern on a transparent substrate. Next, by setting this resist pattern as a mask and etching the shielding layer to form a pattern on the shielding layer, it is possible to obtain a photomask including the shielding layer having a predetermined pattern on the transparent substrate.
However, since it is difficult for an electron beam to collectively expose unlike ultraviolet rays, a resist with high sensitivity is required for reducing the treatment time and as a resist which is suitable for electron beam lithography, a so-called positive-tone resist composition which is a combination of an acid-decomposable polymer compound with a photo-acid generator, and a so-called negative-tone resist composition which is a combination of a cross-linking polymer compound with a cross-linking agent have been effectively used. However, in such a resist composition, when trying to make higher sensitivity, the decrease in resolution, the deterioration of a pattern shape and the occurrence of a scum tend to occur. Furthermore, the deterioration of line edge roughness (a phenomenon in which the edge becomes uneven because a resist pattern and the edge of a substrate interface irregularly changes in the vertical direction to a line, and the accuracy of dimension is decreased by the unevenness being transcribed by an etching process) tends to occur. The improvement of line edge roughness is particularly very important subject in an ultrastructural region in which the line width is 0.25 μm or less.
As a method which solves some of these problems, a photo-acid generator including a cross-linking group in a molecule is disclosed. For example, a compound having a photo-acid generator group and a vinyl ether group which is cross-linked by the generated acid in the same molecule is disclosed in JP2001-19799A. In addition, a compound having a photo-acid generator group and a cross-linking group including a ring structure such as an oxetane ring in the same molecule is disclosed in JP2011-246439A. However, it was difficult to satisfy high sensitivity, high resolution (for example, high resolving power, an excellent pattern shape and small line edge roughness (LER)) and excellent dry etching resistance at the same time depending on the resist compositions using these compounds. In addition, it is speculated that particularly, a compound disclosed in JP2001-19799A has a cross-linking group at a cation part that may be one of the causes, however, the temporal stability is poor, therefore, a non-exposed portion is reacted and this becomes one of the causes of deterioration of a scum.